From one to many islands : the emergence of search and matching models

The notion of frictional unemployment first arose in the writings of Beveridge, Pigou and Hicks. Why did it fail at the time to grow into a fully fledged theory ? Our answer is simple. This failure was due to the fact these economists were unwilling and/or unable to go beyond the then-prevailing Marshallian approach, in particular to depart from its trade organization assumptions. They did not realize that these assumptions excluded any rationing outcome in general, and any unemployment result in particular. We make our claim in three steps. First, we make explicit the trade-organization assumptions underpinning Marshall’s equilibrium theory. Our second step is a study of the attempts at introducing unemployment in a Marshallian framework. We start with an examination of Beveridge’s, Pigou’s and Hicks’s early works on wages and unemployment. We also briefly discuss how and why Keynes was able to shift attention from frictional to involuntary unemployment. Newt, for a reason that will become clear as the paper evolves, we ponder Friedman’s celebrated Presidential Address inaugurating the notion of a natural rate of unemployment. In our third and last step we look at the papers by McCall, Lucas and Prescott, Mortensen and Pissarides that paved the way for the present thriving research literature. We show that their success in providing an equilibrium unemployment result stems from the fact that they have indeed departed from the Marshallian trade-organization assumptionsSupply and Demand; Marshall; Search; Matching

The egalitarian sharing rule in provision of public projects

In this note we consider a society that partitions itself into disjoint jurisdictions, each choosing a location of its public project and a taxation scheme to finance it. The set of public project is multi-dimensional, and their costs could vary from jurisdiction to jurisdiction. We impose two principles, egalitarianism, that requires the equalization of the total cost for all agents in the same jurisdiction, and efficiency, that implies the minimization of the aggregate total cost within jurisdiction. We show that these two principles always yield a core-stable partition but a Nash stable partition may fail to exist.Comment: 7 page

On the sound of snapping shrimp

Fluid dynamics video: Snapping shrimp produce a snapping sound by an extremely rapid closure of their snapper claw. Our high speed imaging of the claw closure has revealed that the sound is generated by the collapse of a cavitation bubble formed in a fast flowing water jet forced out from the claws during claw closure. The produced sound originates from the cavitation collapse of the bubble. At collapse a short flash of light is emitted, just as in single bubble sonoluminescence. A model based on the Rayleigh-Plesset equation can quantitatively account for the visual and acoustical observations.Comment: Fluid dynamics vide

The Egalitarian Sharing Rule in Provision of Public Projects

In this note we consider a society that partitions itself into disjoint jurisdictions, each choosing a location of its public project and a taxation scheme to finance it. The set of public project is multi-dimensional, and their costs could vary from jurisdiction to jurisdiction. We impose two principles, egalitarianism, that requires the equalization of the total cost for all agents in the same jurisdiction, and efficiency, that implies the minimization of the aggregate total cost within jurisdiction. We show that these two principles always yield a core-stable partition but a Nash stable partition may fail to exist.Jurisdictions, Stable partitions, Public projects, Egalitarianism

The Egalitarian sharing rule in provision of public goods

In this note we consider a society that partitions itself into disjoint jurisdictions, each choosing a location of its public project and a taxation scheme to finance it. The set of public project is multi-dimensional, and their costs could vary from jurisdiction to jurisdiction. We impose two principles, egalitarianism, that requires the equalization of the total cost for all agents in the same jurisdiction, and efficiency, that implies the minimization of the aggregate total cost within jurisdiction. We show that these two principles always yield a core-stable partition but a Nash stable partition may fail to exist. We demonstrate moreover that stable partitions are not necessarily consecutive.

Heterogeneity gap in stable juridiction structures

Stability, Jurisdictions, Public Projects, Heterogeneity Gap

The costs of HIV prevention for different target populations in Mumbai, Thane and Bangalore.

BACKGROUND: Avahan, the India AIDS Initiative, delivers HIV prevention services to high-risk populations at scale. Although the broad costs of such HIV interventions are known, to-date there has been little data available on the comparative costs of reaching different target groups, including female sex workers (FSWs), replace with 'high risk men who have sex with men (HR-MSM) and trans-genders. METHODS: Costs are estimated for the first three years of Avahan scale up differentiated by typology of female sex workers (brothel, street, home, lodge based, bar based), HR-MSM and transgenders in urban districts in India: Mumbai and Thane in Maharashtra and Bangalore in Karnataka. Financial and economic costs were collected prospectively from a provider perspective. Outputs were measured using data collected by the Avahan programme. Costs are presented in US$2008. RESULTS: Costs were found to vary substantially by target group. Non-governmental organisations (NGOs) working with transgender populations had a higher mean cost (US$116) per person reached compared to those dealing primarily with FSWs (US $75-96) and MSWs (US$90) by the end of year three of the programme in Mumbai. The mean cost of delivering the intervention to HR-MSMs (US $42) was higher than delivering it to FSWs (US$37) in Bangalore. The package of services delivered to each target group was similar, and our results suggest that cost variation is related to the target population size, the intensity of the programme (in terms of number of contacts made per year) and a number of specific issues related to each target group. CONCLUSIONS: Based on our data policy makers and program managers need to consider the ease of accessing high risk population when planning and budgeting for HIV prevention services for these populations and avoid funding programmes on the basis of target population size alone